1. Technical Field of the Invention
The present invention relates to novel 10-hydroxy-2-decenoic acid compounds and to the use of an effective amount of 10-hydroxy-2-decenoic acid or of at least one derivative thereof for promoting desquamation of the skin and/or to stimulate epidermal renewal and/or to combat aging of the skin.
This invention also relates to hydroxydecenoic compositions for promoting desquamation of the skin and/or for stimulating epidermal renewal and therefore for combating intrinsic and/or extrinsic cutaneous aging, as well as to a nontherapeutic regime/regimen for promoting desquamation and/or to combat aging of the skin.
2. Description of the Prior Art
Desquamation is a natural phenomenon associated with the fact that the epidermis, which constitutes the upper layer of the skin, is in constant regeneration. The epidermis is composed of several layers of cells, the deepest of which is the basal layer consisting of undifferentiated cells. Over time, these cells differentiate and migrate to the surface of the epidermis, constituting the various layers thereof, until they form at the surface of the epidermis the corneocytes, which are dead cells which are eliminated by desquamation. This loss of surface is compensated for by the migration of cells from the basal layer towards the surface of the epidermis. This amounts to perpetual renewal of the skin. Forced elimination of the horny layer accelerates renewal and makes it possible to combat aging.
At the same time, these cells continue their differentiation, the final stage of which is the corneocyte. These are dead cells which constitute the final layer of the epidermis, namely, the outermost layer, also known as the stratum corneum.
Cutaneous skin aging resulting from intrinsic or extrinsic factors is reflected by the appearance of wrinkles and fine lines, by yellowing of the skin, which develops a parchment-like appearance accompanied by the development of pigmentary blemishes, by the disorganization of the elastin and collagen fibers, causing a loss of elasticity, flexibility and firmness, or by the appearance of telangiectases.
Certain of these signs of aging are more particularly associated with intrinsic or physiological aging, namely, with xe2x80x9cnormalxe2x80x9d aging due to age or chronobiological aging, whereas others are more specific to extrinsic aging, namely, aging caused in general by the environment; this relates more particularly to photoaging due to exposure to the sun, to light or to any other radiation.
The present invention relates to not only intrinsic or physiological aging, but also to extrinsic aging.
The changes in the skin due to intrinsic aging are the consequence of a genetically programmed senescence involving endogenous factors. This intrinsic aging causes, in particular, a slowing down of the renewal of the cells of the skin, which is reflected essentially by the appearance of detrimental clinical changes, such as a reduction in the subcutaneous adipose tissue and the appearance of small wrinkles or fine lines, and by histopathological changes, such as an increase in the number and thickness of elastic fibers, a loss of vertical fibers from the membrane of the elastic tissue, and the presence of large irregular fibroblasts in the cells of this elastic tissue.
In contrast, extrinsic aging causes detrimental clinical changes, such as large wrinkles and the formation of a flaccid and weathered skin, and histopathological changes, such as an excessive accumulation of elastic material in the epidermis and degeneration of the collagen fibers.
Various active agents for combating cutaneous aging are known to this art.
Thus, U.S. Pat. No. 4,603,146 describes the use of retinoic acid and derivatives thereof in cosmetic compositions for combating cutaneous aging.
Moreover, numerous patents and publications (see, for example, EP-A-413,528) describe and many commercially available cosmetic compositions include xcex1-hydroxy acids, such as lactic acid, glycolic acid or citric acid, for treating/combating cutaneous aging.
Too, the xcex2-hydroxy acids, and more especially salicylic acid and derivatives thereof, are known for their desquamating properties (see WO-A-93/10756 and U.S. Pat. No. 4,767,750).
All of the aforesaid prior art compounds elicit action against aging of the skin by promoting desquamation, namely, the removal of the xe2x80x9cdeadxe2x80x9d cells located at the surface of the horny layer of the epidermis. This xe2x80x9cdesquamatingxe2x80x9d property is also referred to, often incorrectly, as a keratolytic property.
However, the prior art compounds also present objectionable side effects, such as stinging, pricking, stabbing pains and sensations of heat and redness which are unpleasant for the user.
Need therefore continues to exist for antiaging agents having an action which is at least as effective as that of the compounds of the prior art, but which do not present the disadvantages thereof.
Accordingly, a major object of the present invention is the provision of novel compounds and active agents which promote desquamation of the skin and/or which stimulate epidermal renewal, while at the same time avoiding the stinging, pricking, stabbing pains or sensations of heat or redness which are unpleasant for the user and which to date have characterized the state of this art.
10-Hydroxy-2-decenoic acid is present in the trans form in royal jelly, constituting approximately 10% of the dry mass thereof and from which it was extracted for the first time in 1940 by Townsend and Lucas (Biochem. J., 34, 1155 (1940)).
10-Hydroxy-2-decenoic acid in the trans form is implicated in the differentiation of the female castes in bees.
In the prior art, this acid has been formulated into compositions for the prevention of leukemias, depigmentary compositions, compositions having activity with regard to the loss and regrowth of hairs and heads of hair, antiseborrhoeic compositions, antitumoral compositions or bacteriostatic compositions.
Heretofore, however, it had not been recognized that 10-hydroxy-2-decenoic acid or any derivative thereof could be administered for promoting desquamation of the skin and/or stimulating epidermal renewal and therefore combating intrinsic and/or extrinsic cutaneous aging.
Thus, it has now unexpectedly and surprisingly been determined that administering an effective amount of 10-hydroxy-2-decenoic acid or of at least one particular derivative thereof promotes desquamation of the skin and/or stimulates epidermal renewal and, hence, is useful for combating skin aging.